I’ve posted before about my grandson’s journey in learning English consonants. My earlier post is at https://languagemiscellany.com/2021/07/learning-some-english-consonants/ It comments on how he was pronouncing some consonants at the age of 3 years, 6 months.
He is now 3 years, 11 months and is still doing what I recorded in that post. He regularly, especially at the beginning of words:
- produces stops (such as d and b) instead of fricatives (such as s and f); but
- produces the fr (fricative followed by an approximant) instead of the sequence gr (a stop followed by that approximant).
A new example
I recently noticed a new example. We were talking about various fruits and he pronounced plum as flum. So in that case he is again producing the sequence fricative then approximant (fl) instead of the adult form, which is stop then approximant (pl).
Immature perception or immature production?
The first aspect of his pronunciation discussed above is producing stops instead of fricatives. In my earlier post, I commented on where this aspect sits. I concluded that it sits within his production system rather than within his perception system. He can distinguish stops from fricatives, but can’t (or won’t) produce the fricatives in some sound sequences.
The second aspect discussed above is introducing an initial fricative instead of keeping the adult stop in some sequences.
I have tended to assume that this second aspect is also part of his production system, not part of his perception system. I haven’t tried to test this though. It might be difficult to test it, because other family members often tease him by imitating his pronunciation of Gran as Fran and Grandad as Franfrad, so he is probably quite conscious of these particular words and it may be hard to get a completely natural response from him.
I did try to test this second aspect recently with the new example (plum pronounced as flum). I showed him a plum and asked whether it was a plum or a flum. He said yes to plum, not to flum. That answer provides some weak support for my assumption that this particular feature is part of the production system, not part of the perception system. But my little experiment didn’t test this rigorously.
A parallel with German
My grandson’s pronunciation of plum as flum shows an interesting partial parallel with a sound change in German known as the High German consonant shift (or the second Germanic consonant shift). In some German words, an original stop (for example, [p]) was replaced by an affricate (for example, [pf]). Thus, the German word for plum is Pflaume. Other German words this sound change led to [pf] where English kept [p] include Pfad (English path), Pfeffer (English pepper), Pflug (English plough) and Apfel (English apple).
As I said, this is only a partial parallel because he produces a fricative [fl] in plum, whereas the second German consonant shift led to an affricate [pf] in Pflaume.
A sketch of an analysis using autosegmental tiers
The theory (or theories) known as autosegmental phonology provide a neat way of thinking about what is going on in such cases. This theory sees a sound as being made up not of a monolithic block of features but as the product of a set of features sitting on various tiers (layers or dimensions). A feature on one tier does not necessarily have the same duration as a feature on another tier. Also, phonological processes can change the relative durations. The following two diagrams illustrate this idea.
How an adult says it
Diagram 1 illustrates the adult pronunciation of the sequence [pl] in [plum]. The two columns depict two of the features that make up the first two sounds in [plum].
- the first consonant in the sequence has features that include labial (made with the lips) and -continuant (not continuant, in other words, a stop). The first consonant surfaces as a sound with those features: [p]
- the second consonant in the sequence has features that include lateral (the tongue is is in a position that forces air to flow round it) and +continuant (ie not a stop). The second consonant surfaces as a sound with those features: [l]
So an adult pronounces the first two sounds as the sequence [pl]

How a 3 year old says it
Diagram 2 illustrates my grandson’s pronunciation.

- the first consonant is still labial and the second consonant is still lateral.
- the first consonant is no longer linked to the feature – continuant. Depending on the theory used, it is either deleted entirely or just disconnected from the other features.
- the feature + connected spreads from the second consonant to the first consonant. As a result, it now applies to both consonants. The first consonant now surfaces as a continuant labial: [f]. Just as in diagram 1, the second consonant is a lateral continuant and still surfaces as [l]
So my grandson pronounces the sequence [pl] as [fl]. He gets there simply by talking a feature already present in the adult [l] and extending it to cover the initial [p], converting that into [f].
In the above diagrams, the features +continuant / -continuant sit on their own tier, which is separate from the tier (or tiers) containing the features labial and lateral. The spreading shown in diagram 2 makes the +continuant feature last longer. As a result, it overlaps with the whole of the labial feature and then with the whole of the lateral feature.
Conclusion
Although my grandson hasn’t fully mastered the English sound system, he is not just producing random sounds. There are systematic differences between his sound system and the sound system of an adult native speaker. It will be interesting to see how the differences narrow as his language matures further.